The recently discovered oxide superconducting ceramic materials, with superconducting transition temperatures (T.sub.c) in the range above that of liquid nitrogen (77.degree. K), are technologically very exciting materials. However, they are not known to suffer extensive chemical degradation in the atmosphere, particularly in the presence of water vapour and carbon dioxide. In addition, they are highly oxidising and are able to oxidise metals, including gold, in bulk solution and in condensed moisture films. This reactivity will limit their eventual use and methods of eliminating the degradation must be sought prior to commercial exploitation.
It is therefore an object of the present invention to provide a method of protecting such superconductors from degradation.